Cutting and welding of aluminum with a high-repetition-rate pulsed CO2 laser

Publisher Website
Google Scholar
Abstract
The high reflection and the high thermal conductivity of aluminum make it difficult to transfer the laser energy into the workpiece. For high energy transfer efficiencies a multikilohertz repetition rate laser system with high average power and high peak power is required. By using a Q-switched CO2 laser oscillator amplifier system laser pulses of 70 mJ energy, 0.2 ps half width and 250 kW peak power with a repetition rate of 20 kllz, an average power of 1.4 kW and TEM00 mode quality are available. The pulsed laser system allows the cutting of aluminum plates with a higher velocity and a better quality than it can be reached with a cw laser at comparable average power. Using laser pulses burr free cutting of aluminum up to 10 mm thickness at moderate average laser power level is possible, because a laser-induced plasma is ignited within the gap by each laser pulse. For welding of aluminum plates the laser pulses of the Q-switched laser system can be shaped to achieve an optimized energy transfer into the material and a good welding quality. The electron density of the welding plasma plays an important role for the energy transfer. The spatial and temporal distribution of the electron density in a laser-induced plasma is measured by a beam deflection technique. The electron density can be influenced by the working gas and the laser pulse form. Typical values 1.2 mm above the aluminum surface are for example 3 . 1023 m3 in case of argon as working gas and 1 . 1023 m3 in case of helium.

This publication has 0 references indexed in Scilit: